scholarly journals ISOLATION, CHARACTERIZATION AND FORMULATION OF ANTAGONISTIC BACTERIA AGAINST FUNGAL PLANT PATHOGENS

AGROFOR ◽  
2019 ◽  
Vol 3 (3) ◽  
Author(s):  
Natalija ATANASOVA-PANCEVSKA ◽  
Dzoko KUNGULOVSKI
Keyword(s):  
Plant Pathogens ◽  
Storage Period ◽  
Plasmopara Viticola ◽  
Antagonistic Bacteria ◽  
Biochemical Tests ◽  
Crop Losses ◽  
Antagonistic Bacterium ◽  
Fungal Plant Pathogens ◽  
Paenibacillus Alvei

Concerns regarding food safety and the environment have led to reduced use ofagrochemicals and the development of sustainable agriculture. In this context,biological control of fungal plant pathogens can improve global food availability,one of the three pillars of food security, by reducing crop losses, particularly forlow-income farmers. Antagonistic bacteria are common soil inhabitants withpotential to be developed into biofungicides for the management of fungal plantpathogens. In this study, antagonistic bacterium was isolated from the commercialcompost from a Resen factory for compost and screened for its growth inhibition offungal pathogens in laboratory tests. The zone of inhibition (mm) was recorded bymeasuring the distance between the edges of the growing mycelium and theantagonistic bacterium. Five replications were maintained for each isolate. Basedon phenotypic characteristics, biochemical tests, and sequence analysis of 16SrRNA, the antagonistic bacterium was identified as Paenibacillus alvei (strain DZ-3). The bacterium suppressed the growth of all five tested fungal plant pathogens(Fusarium oxysporum, Rhizoctonia solani, Alternaria alternata, Botrytis cinereaand Plasmopara viticola) in in vitro conditions over. The survival of antagonisticbacterium in peat and talc formulations decreased time at room temperature, butthe populations remained above 108 CFU/g during the 180-day storage period. Thisstudy suggests that this bacterium can be developed and formulated asbiofungicides for minimizing the crop losses caused by fungal plant pathogens anddiseases caused by them.

Isolation, characterization, and formulation of antagonistic bacteria for the management of seedlings damping-off and root rot disease of cucumber

2014 ◽  
Vol 60 (1) ◽  
pp. 25-33 ◽  
Author(s):  
Salah Eddin Khabbaz ◽  
Pervaiz A. Abbasi
Keyword(s):  
Plant Growth ◽  
Root Rot ◽  
Storage Period ◽  
Pythium Ultimum ◽  
In Vitro Tests ◽  
Antagonistic Bacteria ◽  
Damping Off ◽  
Biochemical Tests ◽  
Cucumber Seedlings

Antagonistic bacteria are common soil inhabitants with potential to be developed into biofungicides for the management of seedling damping-off, root rot, and other soil-borne diseases of various crops. In this study, antagonistic bacteria were isolated from a commercial potato field and screened for their growth inhibition of fungal and oomycete pathogens in laboratory tests. The biocontrol potential of the 3 most effective antagonistic bacteria from the in vitro tests was evaluated against seedling damping-off and root rot of cucumber caused by Pythium ultimum. Based on phenotypic characteristics, biochemical tests, and sequence analysis of 16S–23S rDNA gene, the 3 antagonistic bacteria were identified as Pseudomonas fluorescens (isolate 9A-14), Pseudomonas sp. (isolate 8D-45), and Bacillus subtilis (isolate 8B-1). All 3 bacteria promoted plant growth and suppressed Pythium damping-off and root rot of cucumber seedlings in growth-room assays. Both pre- and post-planting application of these bacteria to an infested peat mix significantly increased plant fresh masses by 113%–184% and percentage of healthy seedlings by 100%–290%, and decreased damping-off and root rot severity by 27%–50%. The peat and talc formulations of these antagonistic bacteria applied as seed or amendment treatments to the infested peat mix effectively controlled Pythium damping-off and root rot of cucumber seedlings and enhanced plant growth. The survival of all 3 antagonistic bacteria in peat and talc formulations decreased over time at room temperature, but the populations remained above 108CFU/g during the 180-day storage period. The peat formulation of a mixture of 3 bacteria was the best seed treatment, significantly increasing the plant fresh masses by 245% as compared with the Pythium control, and by 61.4% as compared with the noninfested control. This study suggests that the indigenous bacteria from agricultural soils can be developed and formulated as biofungicides for minimizing the early crop losses caused by seedling damping-off and root rot diseases.

scholarly journals Evaluation of in-vitro methods to select effective streptomycetes against toxigenic fusaria

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6905 ◽  
Author(s):  
Elena Maria Colombo ◽  
Cristina Pizzatti ◽  
Andrea Kunova ◽  
Claudio Gardana ◽  
Marco Saracchi ◽  
...  
Keyword(s):  
Plant Pathogens ◽  
Culture Media ◽  
Screening Methods ◽  
Dual Culture ◽  
In Planta ◽  
In Vitro Method ◽  
In Vitro Methods ◽  
Strain Diversity ◽  
Fungal Plant Pathogens

Biocontrol microorganisms are emerging as an effective alternative to pesticides. Ideally, biocontrol agents (BCAs) for the control of fungal plant pathogens should be selected by an in vitro method that is high-throughput and is predictive of in planta efficacy, possibly considering environmental factors, and the natural diversity of the pathogen. The purpose of our study was (1) to assess the effects ofFusariumstrain diversity (N= 5) and culture media (N= 6) on the identification of biological control activity ofStreptomycesstrains (N= 20) againstFusariumpathogens of wheat in vitro and (2) to verify the ability of our in vitro screening methods to simulate the activity in planta. Our results indicate that culture media,Fusariumstrain diversity, and their interactions affect the results of an in vitro selection by dual culture assay. The results obtained on the wheat-based culture media resulted in the highest correlation score (r= 0.5) with the in planta root rot (RR) inhibition, suggesting that this in vitro method was the best predictor of in planta performance of streptomycetes against Fusarium RR of wheat assessed as extension of the necrosis on the root. Contrarily, none of the in vitro plate assays using the media tested could appropriately predict the activity of the streptomycetes against Fusarium foot rot symptoms estimated as the necrosis at the crown level. Considering overall data of correlation, the activity in planta cannot be effectively predicted by dual culture plate studies, therefore improved in vitro methods are needed to better mimic the activity of biocontrol strains in natural conditions. This work contributes to setting up laboratory standards for preliminary screening assays ofStreptomycesBCAs against fungal pathogens.

scholarly journals SKRINING BAKTERI ANTAGONIS RALSTONIA SP., PENYEBAB PENYAKIT LAYU BAKTERI PISANG DI LAMPUNG

2007 ◽  
Vol 7 (2) ◽  
pp. 100-110
Author(s):  
Titik Nur Aeny ◽  
Radix Suharjo ◽  
Subli Mujim
Keyword(s):  
Bacterial Wilt ◽  
Plant Disease ◽  
Hypersensitive Reaction ◽  
Soil Samples ◽  
Causal Agent ◽  
Antagonistic Bacteria ◽  
Bacterial Identification ◽  
Biochemical Tests ◽  
Colony Color

Screening on Antagonistic Bacteria of Ralstonia sp., the Causal Agent of Banana Bacterial Wilt in Lampung. This study was conducted on May to October 2006. This study was aimed to screen and collect potential bacterial antagonists toward Ralstonia sp., the causal agent of banana bacterial wilt; to identify the collected potential antagonists, and to test the capability of the bacterial antagonist in vitro. A survey to collect soil samples was conducted in 5 districts in Lampung, namely Bandar Lampung, Lampung Selatan, Tanggamus, Lampung Utara, Lampung Tengah, and Lampung Timur. Identification and test of the antagonistic capability was done in the Plant Disease Laboratory, University of Lampung. Identification of the antagonist bacteria was done through several biochemical tests i.e. : gram reaction, hypersensitive reaction on tobacco, oxidative-fermentative, colony color on YDC medium, fluoresence, nitrate reduction, gelatin reduction and starch hydrolise.  The results were then compared to the guidelines of bacterial identification. Twenty one soil samples were collected from those surveyed areas to isolate antagonist bacteria, and 104 isolates were found to be antagonistic to Ralstonia sp.. Based on the biochemical tests, it was showed that 59 isolates were in the group of fluorecent pseudomonad and 45 ones were still unidentified. Out of 104 isolates found, 41 isolates have the ability to inhibit the growth of Ralstonia sp.

scholarly journals Plant Defensin Peptides have Antifungal and Antibacterial Activity Against Human and Plant Pathogens

2019 ◽  
Vol 109 (3) ◽  
pp. 402-408 ◽  
Author(s):  
Andrew E. Sathoff ◽  
Siva Velivelli ◽  
Dilip M. Shah ◽  
Deborah A. Samac
Keyword(s):  
Antibacterial Activity ◽  
Plant Pathogens ◽  
Crown Rot ◽  
Plant Defensin ◽  
Core Motif ◽  
Potential Control ◽  
Fungal Plant Pathogens ◽  
Plant Defensins ◽  
Animal Pathogens

Plant defensins are small, cysteine-rich antimicrobial peptides. These peptides have previously been shown to primarily inhibit the growth of fungal plant pathogens. Plant defensins have a γ-core motif, defined as GXCX3-9C, which is required for their antifungal activity. To evaluate plant defensins as a potential control for a problematic agricultural disease (alfalfa crown rot), short, chemically synthesized peptides containing γ-core motif sequences were screened for activity against numerous crown rot pathogens. These peptides showed both antifungal and, surprisingly, antibacterial activity. Core motif peptides from Medicago truncatula defensins (MtDef4 and MtDef5) displayed high activity against both plant and human bacterial pathogens in vitro. Full-length defensins had higher antimicrobial activity compared with the peptides containing their predictive γ-core motifs. These results show the future promise for controlling a wide array of economically important fungal and bacterial plant pathogens through the transgenic expression of a plant defensin. They also suggest that plant defensins may be an untapped reservoir for development of therapeutic compounds for combating human and animal pathogens.

Antifungal activity of extracts from endophytic fungi associated with Smallanthus maintained in vitro as autotrophic cultures and as pot plants in the greenhouse

2012 ◽  
Vol 58 (10) ◽  
pp. 1202-1211 ◽  
Author(s):  
Luiz H. Rosa ◽  
Nurhayat Tabanca ◽  
Natascha Techen ◽  
Zhiqiang Pan ◽  
David E. Wedge ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Endophytic Fungi ◽  
Plant Pathogens ◽  
Cultivation Conditions ◽  
Smallanthus Sonchifolius ◽  
Fungal Plant Pathogens ◽  
In The Wild ◽  
Fungal Assemblages ◽  
Pot Plants

The endophytic fungal assemblages associated with Smallanthus sonchifolius (Poepp.) H. Rob. and Smallanthus uvedalius (L.) Mack. ex Small growing in vitro autotrophic cultures and in the greenhouse were identified and evaluated for their ability to produce bioactive compounds. A total of 25 isolates were recovered that were genetically closely related to species of the genera Bionectria , Cladosporium , Colletotrichum , Fusarium , Gibberella , Hypocrea , Lecythophora , Nigrospora , Plectosphaerella , and Trichoderma . The endophytic assemblages of S. sonchifolius presented a greater diversity than the group isolated from S. uvedalius and demonstrated the presence of dominant generalist fungi. Extracts of all fungi were screened against the fungal plant pathogens. Ten extracts (41.6%) displayed antifungal activities; some of them had a broad antifungal activity. The phylotypes Lecythophora sp. 1, Lecythophora sp. 2, and Fusarium oxysporum were isolated from in vitro autotrophic cultures and displayed antifungal activity. The presence of bioactive endophytic fungi within S. sonchifolius and S. uvedalius suggests an ecological advantage against pathogenic attacks. This study revealed reduced numbers of endophytes in association with both Smallanthus species in controlled cultivation conditions compared with the endophytic communities of hosts collected in the wild environments. Even as reduced endophytic communities, these fungi continue to provide chemical protection for the host.

Douglas-fir root-associated microorganisms with inhibitory activity towards fungal plant pathogens and human bacterial pathogens

1996 ◽  
Vol 42 (7) ◽  
pp. 690-700 ◽  
Author(s):  
Paige E. Axelrood ◽  
Alison M. Clarke ◽  
Reed Radley ◽  
S. Janet V. Zemcov
Keyword(s):  
Antifungal Activity ◽  
Inhibitory Activity ◽  
Plant Pathogens ◽  
Bacterial Pathogens ◽  
Douglas Fir ◽  
Microbial Culture ◽  
Bacterial Strains ◽  
Fungal Plant Pathogens ◽  
Forest Sites

A microbial culture collection composed of 1820 bacterial strains, including 298 actinomycete strains, was established from the roots of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings harvested from conifer nurseries and forest sites. Two hundred and thirty-four strains inhibited the growth of Fusarium, Cylindrocarpon, and (or) Pythium spp. in in vitro assays. A significantly greater proportion of bacterial strains from actinomycete genera exhibited antifungal properties compared with bacterial strains from nonactinomycete genera. Eighty-nine percent of identified inhibitory strains were Streptomyces, Streptoverticillium, Bacillus, Pseudomonas, or Burkholderia species. The actinomycete species were isolated almost exclusively from forest seedlings. Recovery of inhibitory strains representing 29 microbial species was enhanced using a variety of methods to isolate microorganisms from the roots of seedlings from nursery and forest sites. Bacterial strains (including actinomycete strains) with antifungal activity were tested for in vitro growth inhibition of six clinical human bacterial pathogens (Enterococcus faecalis, Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli, Proteus mirabilis, and Pseudomonas aeruginosa). Forty-eight percent of the tested strains inhibited one or more human pathogens. Inhibitory activity towards fungal and bacterial pathogens was strain specific, not species specific, and many inhibitory strains exhibited broad-spectrum activity. Strains with antifungal activity against several conifer root pathogens were also more likely to inhibit multiple species of clinical bacterial pathogens.Key words: in vitro, antimicrobial, conifer rhizosphere.

scholarly journals Sensitivity of Bacterial and Fungal Plant Pathogens to the Lytic Peptides, MSI-99, Magainin II, and Cecropin B

2002 ◽  
Vol 15 (7) ◽  
pp. 701-708 ◽  
Author(s):  
Ali R. Alan ◽  
Elizabeth D. Earle
Keyword(s):  
Phytophthora Infestans ◽  
Plant Pathogens ◽  
Fungal Spores ◽  
Alternaria Solani ◽  
Leaf Disk ◽  
Cecropin B ◽  
Fungal Plant Pathogens ◽  
Magainin Ii ◽  
Lytic Peptides

In vitro and leaf disk assays of bacterial and fungal plant pathogens were conducted using three cationic lytic peptides, MSI-99, magainin II (MII), and cecropin B (CB). Growth of bacterial organisms was retarded or completely inhibited by low concentrations of these lytic peptides. The peptides also significantly reduced germination of fungal spores and growth of mycelia; however, higher concentrations of peptides were needed to inhibit fungal growth compared with those needed to inhibit bacteria. The relative efficacy of the peptides depended on the microorganism tested, but CB was the most inhibitory to the majority of the bacteria and fungi assayed. MSI-99, a synthetic derivative of MII with increased positive charge, showed equal or two- to fivefold higher antibacterial activity compared to MII in the in vitro assays. MSI-99 was also superior to MII against the oomycete, Phytophthora infestans but was slightly inferior to MII in assays with the true fungi, Penicillium digitatum and Alternaria solani. In the leaf disk assays, pretreating spores of Alternaria solani and Phytophthora infestans with the peptides at concentrations as low as 10 μg per ml led to significant reductions in the size of early blight lesions and prevented development of any late blight lesions on tomato leaf disks. Our results from in vitro and leaf disk assays suggest that MSI-99 can be used as a transgene to generate tomato lines with enhanced resistance to bacterial and fungal diseases of this crop.

scholarly journals Transfection of Sclerotinia sclerotiorum withIn VitroTranscripts of a Naturally Occurring Interspecific Recombinant of Sclerotinia sclerotiorum Hypovirus 2 Significantly Reduces Virulence of the Fungus

2015 ◽  
Vol 89 (9) ◽  
pp. 5060-5071 ◽  
Author(s):  
Shin-Yi Lee Marzano ◽  
Houston A. Hobbs ◽  
Berlin D. Nelson ◽  
Glen L. Hartman ◽  
Darin M. Eastburn ◽  
...  
Keyword(s):  
Sclerotinia Sclerotiorum ◽  
Plant Pathogens ◽  
High Throughput Sequencing ◽  
Infectious Clone ◽  
White Mold ◽  
Content Type ◽  
Fungal Plant Pathogens ◽  
Rapid Amplification ◽  
Valsa Ceratosperma

ABSTRACTA recombinant strain ofSclerotinia sclerotiorumhypovirus 2 (SsHV2) was identified from a North AmericanSclerotinia sclerotiorumisolate (328) from lettuce (Lactuca sativaL.) by high-throughput sequencing of total RNA. The 5′- and 3′-terminal regions of the genome were determined by rapid amplification of cDNA ends. The assembled nucleotide sequence was up to 92% identical to two recently reported SsHV2 strains but contained a deletion near its 5′ terminus of more than 1.2 kb relative to the other SsHV2 strains and an insertion of 524 nucleotides (nt) that was distantly related toValsa ceratospermahypovirus 1. This suggests that the new isolate is a heterologous recombinant of SsHV2 with a yet-uncharacterized hypovirus. We named the new strainSclerotinia sclerotiorumhypovirus 2 Lactuca (SsHV2L) and deposited the sequence in GenBank with accession numberKF898354.Sclerotinia sclerotiorumisolate 328 was coinfected with a strain ofSclerotinia sclerotiorumendornavirus 1 and was debilitated compared to cultures of the same isolate that had been cured of virus infection by cycloheximide treatment and hyphal tipping. To determine whether SsHV2L alone could induce hypovirulence inS. sclerotiorum, a full-length cDNA of the 14,538-nt viral genome was cloned. Transcripts corresponding to the viral RNA were synthesizedin vitroand transfected into a virus-free isolate ofS. sclerotiorum, DK3. Isolate DK3 transfected with SsHV2L was hypovirulent on soybean and lettuce and exhibited delayed maturation of sclerotia relative to virus-free DK3, completing Koch's postulates for the association of hypovirulence with SsHV2L.IMPORTANCEA cosmopolitan fungus,Sclerotinia sclerotioruminfects more than 400 plant species and causes a plant disease known as white mold that produces significant yield losses in major crops annually. Mycoviruses have been used successfully to reduce losses caused by fungal plant pathogens, but definitive relationships between hypovirus infections and hypovirulence inS. sclerotiorumwere lacking. By establishing a cause-and-effect relationship betweenSclerotinia sclerotiorumhypovirus Lactuca (SsHV2L) infection and the reduction in host virulence, we showed direct evidence that hypoviruses have the potential to reduce the severity of white mold disease. In addition to intraspecific recombination, this study showed that recent interspecific recombination is an important factor shaping viral genomes. The construction of an infectious clone of SsHV2L allows future exploration of the interactions between SsHV2L andS. sclerotiorum, a widespread fungal pathogen of plants.

scholarly journals Diversity of biocontrol agents, isolated from several sources, inhibitory to several fungal plant pathogens

2020 ◽  
Vol 22 (1) ◽  
Author(s):  
Yan Ramona ◽  
IDA BAGUS GEDE DARMAYASA ◽  
ANAK AGUNG NGURAH NARA KUSUMA ◽  
Martin Line
Keyword(s):  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Antagonistic Activity ◽  
Significant Inhibition ◽  
Biocontrol Agents ◽  
Dual Culture ◽  
Rdna Sequences ◽  
Fungal Plant Pathogens ◽  
Mature Compost

Abstract. Ramona Y, Darmayasa IBG, Kusuma AANN, Line MA. 2021. Diversity of biocontrol agents, isolated from several sources, inhibitory to several fungal plant pathogens. Biodiversitas 22: 298-303. This study investigated the inhibitory potential of diversity of antagonist bacteria residing in the rhizosphere zone and mature compost to counter fungal plant pathogens. Soils collected from rhizosphere of lettuce farms in Bali-Indonesia and Tasmania-Australia, mature compost, commercial biocontrol (Dipel®), and laboratory contaminants with significant inhibition against tested fungal pathogens were used as sources of antagonist bacteria. These antagonists were isolated by applying dilution and spread method on trypticase soya agar (TSA) or potato dextrose agar (PDA), and their ability to inhibit Sclerotinia minor, Sclerotinia sclerotiorum, Fusarium spp., and Rhizoctonia solani was assessed in dual culture assays. The results showed that 67 out of more than 100 isolates had antagonistic activity in vitro against at least one of tested fungal pathogens. In the preliminary identification, Bacillus spp. or Pseudomonas spp. were found to be pre-dominant isolates. Following screening studies in a non-replicated glasshouse experiment against S. minor and S. sclerotiorum, 8 of the most promising isolates were further identified using molecular methods based on their 16s rDNA sequences aligned with those deposited at the GeneBank. These 8 isolates were identified as Pseudomonas corrugata, Bacillus megaterium, Bacillus polymyxa, Bacillus mojavensis, Bacillus pumilus, Bacillus thuringiensis, Exiguobacterium acetylicum, and Chryseobacterium indologenes.

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